Mechanics

CEL, ROUGH IDLE AND OBVIOUS MISFIRE AT

1998 Chrysler Cirrus

Engine Performance problem
1998 Chrysler Cirrus 6 cyl Front Wheel Drive Automatic 112000 miles

Car idles somewhat rough, misses significantly under load above 5500rpm and sets the following 9 codes:

P1391 - Loss of Cam or Crank
P300-306 - Multiple random misfire, Misfire on 1, 2, 3, 4 5, 6

Sometimes it idles better (such as immediately after installing new EGR, but it's worsened again now) and sometimes it runs without misfiring at speed, but the CEL comes on every time I clear it with at least the P300 and several cylinder misfire codes. So, symptoms vary, but the core problem (CEL and random misfire) remains.

Replaced the following very recently, most by me:

. New distributor, cap and rotor (twice, second time by mechanic)
. Timing belt (by mechanic)
. New plugs (gapped) and wires
. New crank sensor (spacer was in place on tip, so gap should be correct)
. EGR valve, gasket and solenoid
. Both EGR tube gaskets
. EGR solenoid-to-manifold vacuum tubing

Also have run drygas & fuel injector cleaner.

The problem started about 5000-miles ago with a " loss of cam or crank" code, two short misfire episodes on the way home and then a no-start in my driveway. At that time I replaced the distributor, cap, rotor, plugs, wires and crank sensor, and got it to run, but it still missed badly under load, and seemed to smooth when I wiggled the wires at the distributor. Then it went to a trusted mechanic for the t-belt and another new distributor assembly, as he felt the NAPA part I'd installed was faulty. After replacing the distributor, he was unable to get a miss by wiggling the distributor wires. He got it to run without a code for about a couple of days, but the code returned. He then helped me trace down a vacuum leak at the EGR tube, which I replaced.
Avatar
Opk73
February 4, 2010.




TEST TC-157A: INTERMITTENT LOSS OF CMP OR CKP 1. Camshaft Position (CMP) sensor or Crankshaft Position (CKP) sensor signal loss can be detected by a pattern on an oscilloscope. If this trouble code is being diagnosed with an oscilloscope, go to next step. If this trouble code is not being diagnosed with an oscilloscope, go to TEST TC-157B . 2. Using oscilloscope voltage lead, backprobe CMP sensor signal circuit at CMP sensor connector. See CMP SENSOR CONNECTOR WIRE IDENTIFICATION table. Start engine. Observe CMP sensor voltage pattern on oscilloscope. If any CMP sensor signals are missing, go to next step. If any CMP sensor signals are not missing, go to step 6) . 3. Turn ignition off. Disconnect CMP sensor connector. Inspect CMP sensor connector for pushed out terminals or damage. Repair CMP sensor connector as necessary. Perform TEST VER-2A . If CMP sensor is okay, go to next step. 4. Disconnect Powertrain Control Module (PCM) connector. Inspect PCM connector for pushed out terminals or damage. Repair PCM connector as necessary. Perform TEST VER-2A . If PCM connector is okay, go to next step. 5. Remove CMP sensor. Inspect pulse ring and sprocket for damage or misalignment. Repair or replace as necessary. Perform TEST VER-2A . If pulse ring and sprocket are okay, replace CMP sensor. Perform TEST VER-2A . 6. Using oscilloscope voltage lead, backprobe CMP sensor signal circuit at PCM connector terminal No. 33. See PCM CONNECTOR WIRE IDENTIFICATION table. While observing oscilloscope pattern, wiggle wiring harness from CMP sensor connector to PCM connector. If any signals were missing when wiring harness was wiggled, repair wiring harness as necessary where wiggling caused problem to appear. Perform TEST VER-2A . If signals were not missing when wiring harness was wiggled, go to next step. 7. Turn ignition off. Using oscilloscope voltage lead, backprobe CKP sensor signal circuit. See CKP SENSOR CONNECTOR WIRE IDENTIFICATION table. Start engine. Observe CKP sensor voltage pattern on oscilloscope. If any CKP sensor signals are missing, go to next step. If any CMP sensor signals are not missing, go to step 10) . 8. Turn ignition off. Disconnect CKP sensor connector. Inspect CKP sensor connector for pushed out terminals or damage. Repair CKP sensor connector as necessary. Perform TEST VER- 2A . If CKP sensor is okay, go to next step. 9. Disconnect Powertrain Control Module (PCM) connector. Inspect PCM connector for pushed out terminals or damage. Repair PCM connector as necessary. Perform TEST VER-2A . If PCM connector is okay, replace CKP sensor. Perform TEST VER-2A . 10. Using oscilloscope voltage lead, backprobe CKP sensor signal circuit at PCM connector terminal No. 32. See PCM CONNECTOR WIRE IDENTIFICATION table. While observing oscilloscope pattern, wiggle wiring harness from CKP sensor connector to PCM connector. If any signals were missing when wiring harness was wiggled, repair wiring harness as necessary where wiggling caused problem to appear. Perform TEST VER-2A . If signals were not missing when wiring harness was wiggled, go to next step. 11. Condition to set trouble code is not present at this time. INTERMITTENT LOSS OF CMP OR CKP DTC sets if expected cam signal level disagrees with actual cam signal level. Possible causes are: open or shorted 8-volt supply circuit, open sensor ground, open or shorted signal NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article. circuit, excessive clearance between crankshaft sensor and crankshaft pulse ring, excessive clearance between camshaft sensor and target magnet, damaged target magnet, damaged crankshaft pulse ring, failed sensor, failed PCM or loose CMP or CKP sensor connectors. Go to next step. 12. Inspect all related wiring and connectors and repair as necessary. Perform TEST VER-2A TEST VER-2A . If no problems were found with wiring and connectors, see INACTIVE TROUBLE CODE CONDITION . Test is complete. Perform TEST VER-2A . CMP SENSOR CONNECTOR WIRE IDENTIFICATION
2/5/2010 ...TEST TC-40C: NO CRANK REFERENCE SIGNAL AT PCM 1. Remove Crankshaft Position (CKP) sensor. See Fig. 97 , Fig. 98 or Fig. 99 . If vehicle has a 2.0L or 2.4L engine, go to step 3) . If vehicle has a 2.5L engine, go to next step. 2. Inspect flywheel for damage. If flywheel is damaged, repair or replace as necessary. Perform TEST VER-2A . If flywheel is not damaged, replace CKP sensor. Perform TEST VER-2A . 3. Inspect crankshaft notches for damage or debris. If crankshaft notches are damaged, repair or replace crankshaft as necessary. Perform TEST VER-2A . If crankshaft notches are not damaged, replace CKP sensor. Perform TEST VER-2A . NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.


http://www.2carpros.com/forum/automotive_pictures/62217_CKP_9.jpg



http://www.2carpros.com/forum/automotive_pictures/62217_PCM_8.jpg


Can also be cauased by the timing belt being off by a tooth or two! Recheck timing marks. I am sending a PDF about your EGR, there is a revised part for this problem, part# and test is in the file.

Merlin2021
Feb 5, 2010.


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